Magnetoresistive element having a magnetic compound, magnetic memory, magnetic head, and a magnetic recording/reproducing device

ABSTRACT

An example magnetoresistive element includes a first magnetic layer whose magnetization direction is substantially pinned toward one direction; a second magnetic layer whose magnetization direction is changed in response to an external magnetic field; and a spacer layer. At least one of the first magnetic layer and the second magnetic layer includes a magnetic compound layer including a magnetic compound that is expressed by M1 a M2 b O c  (where 5≦a≦68, 10≦b≦73, and 22≦c≦85). M1 is at least one element selected from the group consisting of Co, Fe, and Ni. M2 is at least one element selected from the group consisting of Ti, V, and Cr.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application is a continuation of U.S. application Ser. No.11/902,657 filed Sep. 24, 2007, which claims priority to Japanese PatentApplication No. 2006-265550 filed on Sep. 28, 2006. Each of theseapplications is incorporated herein by reference in its entirety.

FIELD

The present invention relates to a magnetoresistive element, a magneticmemory having the magnetoresistive element, a magnetic head, and amagnetic recording/reproducing apparatus.

BACKGROUND

Nowadays a miniaturization and a higher recording density of the HDD(Hard Disk Drive) are proceeding rapidly, and an increase in recordingdensity is expected much more in the future. An increase in recordingdensity of HDD can be implemented by narrowing a width of the recordingtrack to enhance a track density. However, when a track width isnarrowed, a magnitude of recorded magnetization, i.e., amplitude of arecording signal, becomes small and thus an improvement in a reproducingsensitivity of the MR head (Magnetoresistive head) that reproduces amedium signal is required.

Recently the GMR head including a high-sensitivity spin valve filmutilizing the GMR (Giant Magneto-Resistance effect) is employed. Thespin valve film is a stacked film having such a sandwich structure thata non-magnetic spacer layer is put between two ferromagnetic layers, anda portion having a stacked film structure to produce a change inresistance is called a spin-dependent scattering unit. The magnetizingdirection of one ferromagnetic layer (referred to as a “pin layer” or a“magnetization pinning layer” hereinafter) out of two ferromagneticlayers is fixed by the ferromagnetic layer, or the like. The magnetizingdirection of the other ferromagnetic layer (referred to as a “freelayer” or a “magnetization free layer” hereinafter) can be changed bythe external magnetic field. In the spin valve film, a largemagneto-resistance effect can be obtained by changing a relative angleof the magnetizing direction between two ferromagnetic layers.

As the magnetoresistive element using the spin valve film, there are theCIP (Current In Plane)-GMR element, the CPP (Current Perpendicular toPlane)-GMR element, and the TMR (Tunneling Magneto-Resistance) element.In the CIP-GMR element, a sense current is fed in parallel with asurface of the spin valve film. In the CPP-GMR element and the TMRelement, a sense current is fed in the almost perpendicular direction tothe surface of the spin valve film.

In the type that a current is fed perpendicularly to the film surface, ametal layer is used as the spacer layer in the normal CPP-GMR element,and an insulating layer is used as the spacer layer in the TMR element.

In the future, when a miniaturization of the magnetoresistive element isadvanced with the increase in density of the magnetic head or the MRAMdevice, a higher MR ratio is required of the magnetoresistive element.

In order to improve the magneto-resistance effect, it is important toincrease a spin-dependent scattering factor of the magnetization pinninglayer and the magnetization free layer.

SUMMARY

It is therefore one of objects of the present invention to provide amagnetoresistive element having a high MR ratio, and a magnetic head, amagnetic recording/reproducing apparatus, and a magnetic memory usingsuch magnetoresistive element.

According to a first aspect of the invention, there is provided amagnetoresistive element including: a first magnetic layer whosemagnetization direction is substantially pinned toward one direction; asecond magnetic layer whose magnetization direction is changed inresponse to an external magnetic field; and a spacer layer providedbetween the first magnetic layer and the second magnetic layer. At leastone of the first magnetic layer and the second magnetic layer has amagnetic compound that is expressed by M1_(a)M2_(b)X_(c) (where 5≦a≦68,10≦b≦73, and 22≦c≦85). M1 is at least one element selected from thegroup consisting of Co, Fe, and Ni. M2 is at least one element selectedfrom the group consisting of Ti, V, Cr, and Mn. X is at least oneelement selected from the group consisting of N, O, and C.

According to a second aspect of the invention, there is provided amagnetoresistive element including: a first magnetic layer whosemagnetization direction is substantially pinned toward one direction; asecond magnetic layer whose magnetization direction is changed inresponse to an external magnetic field; and a spacer layer providedbetween the first magnetic layer and the second magnetic layer. At leastone of the first magnetic layer and the second magnetic layer has astacked structure configured by at least one of ferromagnetic thin filmlayers and at least one of magnetic compound layers. The magneticcompound layers have a magnetic compound expressed by M1_(a)M2_(b)X_(c)(where 5≦a≦68, 10≦b≦73, and 22≦c≦85) as a main component. M1 is at leastone element selected from the group consisting of Co, Fe, and Ni. M2 isat least one element selected from the group consisting of Ti, V, Cr,and Mn. X is at least one element selected from the group consisting ofN, O, and C.

According to a third aspect of the invention, there is provided amagnetoresistive head including the magnetoresistive element accordingto one of the first and second aspects.

According to a fourth aspect of the invention, there is provided amagnetic recording/reproducing apparatus including: the magnetoresistivehead according to the third aspect; and a magnetic recording medium.

According to a fifth aspect of the invention, there is provided amagnetic memory including the magnetoresistive element according to oneof the first and second aspects.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a sectional view of a magnetoresistive film of first to fourthexamples according to an embodiment of the present invention;

FIG. 2 is a sectional view of a magnetoresistive film according to afirst variation of the first example;

FIG. 3 is a sectional view of a magnetoresistive film according to asecond variation of the first example;

FIG. 4 is a sectional view of a magnetoresistive film according to athird variation of the first example;

FIG. 5 is a sectional view of a magnetoresistive film according to afourth variation of the first example;

FIG. 6 is a sectional view of a magnetoresistive film according to afifth variation of the first example;

FIG. 7 is a sectional view of a magnetoresistive film of a fifth exampleaccording to the embodiment of the present invention;

FIG. 8 is a sectional view of a magnetoresistive film according to afirst variation of the fifth example;

FIG. 9 is a sectional view of a magnetoresistive film according to asecond variation of the fifth example;

FIG. 10 is a view showing a state that the magnetoresistive elementaccording to the embodiment is incorporated into a magnetic head;

FIG. 11 is a view showing similarly a state that the magneto-resistiveelement according to the embodiment is incorporated into the magnetichead;

FIG. 12 is a pertinent perspective view showing a schematicconfiguration of a magnetic recording/reproducing apparatus;

FIG. 13 is an enlarged perspective view showing a head gimbal assemblyahead of an actuator arm when viewed from a disk side;

FIG. 14 is a view showing an example of a matrix arrangement of amagnetic memory according to the embodiment;

FIG. 15 is a view showing another example of a matrix arrangement of themagnetic memory according to the embodiment;

FIG. 16 is a sectional view showing a substantial part of the magneticmemory according to the embodiment; and

FIG. 17 is a sectional view taken along an XVII-XVII line shown in FIG.16.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, an embodiment according to the present invention will beexplained in detail with reference to the accompanying drawings. In thefollowing description, the same reference numerals are affixed to thesame portions in the following explanation, and their redundantexplanation will be omitted herein.

In the embodiment, new material of the magnetic compound is arranged inat least one layer of the magnetization pin layer (simply referred to as“pin layer”) and the magnetization free layer (simply referred to as“free layer”) of the magnetoresistive film. As the new material of themagnetic compound contained in the free layer and the pin layer of themagnetoresistive film, the magnetic compound expressed by a formulaM1_(a)M2_(b)X_(c) is employed, wherein M1 is at least one type ofmagnetic 3d transition metal element selected from Co, Fe, Ni, M2 is atleast one type of non-magnetic 3d transition metal element selected fromTi, V, Cr, Mn, X is at least one type of nonmetallic element selectedfrom N, O, C, and 5≦a≦68, 10≦b≦73, and 22≦c≦85. Since the above magneticcompound has high spin polarizability, the spin-dependent scatteringeffect is large and the high MR ratio is obtained.

The reason why the above magnetic compound has the high spinpolarizability is given as follows. Since the non-magnetic 3d transitionmetal element has an electronic structure similar to that of themagnetic 3d transition metal element, such metal element is ready tohave a weak magnetism. When the non-magnetic 3d transition metal elementand the magnetic 3d transition metal element are bonded together, theirband structures are changed mutually and thus a magnetism of thenon-magnetic 3d transition metal element appears more conspicuously.Therefore, not only the magnetic 3d transition metal element but alsothe non-magnetic 3d transition metal element contributes to aspin-dependent conduction. Also, when the nonmetallic element is bondedto the above metallic element, a change in band structure of thenon-magnetic 3d transition metal element and the magnetic 3d transitionmetal element can be encouraged. As a result, the band structures of thenon-magnetic 3d transition metal element and the magnetic 3d transitionmetal element near the Fermi surface are changed, and the high spinpolarizability can be obtained.

When an added amount of a composition ratio “b” of the non-magnetic 3dtransition metal element Ti, V, Cr, Mn is too small in the magneticcompound expressed by the formula M1_(a)M2_(b)X_(c), a contribution ofthe non-magnetic 3d transition metal element to the spin-dependentconduction is reduced. Therefore, it is preferable that the compositionratio “b” should be set to 10≦b. However, when an added amount is toolarge, the magnetic 3d transition metal element is reduced relatively,and the bonding between the non-magnetic 3d transition metal element andthe magnetic 3d transition metal element is reduced. Thus, a magnetismof the non-magnetic 3d transition metal element is weakened. Therefore,it is more preferable that the composition ratio “b” should be set to10≦b≦73.

In order to obtain an effect of encouraging a change of the bandstructures of the non-magnetic 3d transition metal element and themagnetic 3d transition metal element, desirably a composition ratio “c”of the nonmetallic element N, O, C in the magnetic compound expressed bythe formula M1_(a)M2_(b)X_(c) should be set to 22≦c. However, when anadded amount is too large, the non-magnetic 3d transition metal elementand the magnetic 3d transition metal element are reduced relatively, andthen an amount of elements to bear the spin-dependent conduction isreduced. Therefore, it is desirable that the composition ratio “c”should be set to 22≦c≦85. In addition, in order to obtain the large spinpolarizability in a situation that this element is bonded to most of theelements contained in the non-magnetic 3d transition metal element andthe magnetic 3d transition metal element, more preferably thecomposition ratio “c” should be set to 30≦c≦75.

When an added amount of a composition ratio “a” of the magnetic 3dtransition metal element Co, Fe, Ni is too small in the magneticcompound expressed by the formula M1_(a)M2_(b)X_(c), the bonding betweenthe non-magnetic 3d transition metal element and the magnetic 3dtransition metal element is reduced. Thus, a magnetism of thenon-magnetic 3d transition metal element is weakened. However, when anadded amount is too large, the composition ratio “b” of the non-magnetic3d transition metal element and the composition ratio “c” of thenonmetallic element are reduced relatively, and then an effect ofincreasing the spin polarizability due to the addition of thenon-magnetic 3d transition metal element and the nonmetallic element, asalready described, is weakened. Therefore, it is more desirable that thecomposition ratio “a” should be set to 5≦a≦68.

As the crystal structure of the magnetic compound, sometimes suchcrystal structure is amorphous in a composition range of the formulaM1_(a)M2_(b)X_(c), especially a composition range of 30≦c≦75 withinwhich the MR ratio is high. Since the spin-dependent scattering surfacebecomes smooth when the crystal structure becomes amorphous, thespin-dependent scattering effect is further enhanced and accordingly ahigher MR ratio can be obtained.

As a film thickness of the layer in which the magnetic compoundexpressed by the formula M1_(a)M2_(b)X_(c) is contained, it is desirablethat the film thickness should be thinned, particularly should be set to5 nm or less, from a viewpoint that a gap length of the spin valve filmis shortened and a viewpoint that a resistance value is increasedunnecessarily. In contrast, since the sufficient spin-dependentscattering effect cannot be obtained when the film thickness is thinnedexcessively, it is desirable that the film thickness should be set to0.5 nm or more. From the above, it is desirable that the film thicknessof the magnetic compound should be set to 0.5 nm or more but 5 nm orless.

As a method of manufacturing a magnetic compound layer, an M1-M2-Xmagnetic compound layer can be manufactured by forming a film made ofM1-M2 alloy material by the sputter and then causing it to react in an Xelement atmosphere. Also, the M1-M2-X magnetic compound layer may bemanufactured by stacking films of pure M1 material and pure M2 materialby the sputter and then causing them to react in an X elementatmosphere. The film(s) may be caused to react in the X elementatmosphere while irradiating simultaneously the ion beam of a rare gassuch as Ar, or the like or the plasma. According to this method, thestable magnetic compound can be manufactured. Also, the film (s) maybeformed by the sputter while using an M1-M2 -X target.

The magnetic layer containing the magnetic compound may have a singlelayer of magnetic compound or a stacked structure of a magnetic compoundlayer and a ferromagnetic thin layer. When the stacked structure isformed, the conventional ferromagnetic material can be employed as theferromagnetic thin layer. When the magnetic compound layer is employedas the free layer, a magnetic field responsibility can be improved byattacking a soft magnetic film that is superior in the soft magneticcharacteristic to the magnetic compound layer. Also, the magneticcompound layer is employed as the pin layer, the pin characteristic canbe improved by stacking a film made of the material that is pinned moreeasily in one direction.

FIRST EXAMPLE

Examples of the present invention will be explained with reference tothe drawings hereinafter.

FIG. 1 is a sectional view of a magnetoresistive element according to afirst example of the embodiment according to the present invention.

The magnetoresistive element in FIG. 1 includes a lower electrode 21, aunder layer 11, a pinning layer 12, a pin layer 13, a spacer layer 14, afree layer 15, a cap layer 16, and an upper electrode 22, which areformed sequentially from the bottom on a substrate. Out of them, the pinlayer 13, the spacer layer 14, and the free layer correspond to a spinvalve film (spin-dependent scattering unit) that is formed by puttingthe spacer layer 14 between two ferromagnetic layers.

In the first example, a synthetic spin valve structure is given, and themagnetic compound expressed by the formula M1aM2bXc is employed as anupper pin layer 133 of the pin layer 13 located on the spacer side andthe free layer 15. In the first example, Co—Ti—O whose composition ratiois changed is employed as the formula M1_(a)M2_(b)X_(c).

Herein, each of the layers of the magnetoresistive element will bedescribed.

The lower electrode 21 is the electrode that feeds current to themagnetoresistive film in the direction perpendicular to the filmsurface. When a voltage is applied between the lower electrode 21 andthe upper electrode 22, sense current flows through the magnetoresistivefilm in the direction perpendicular to the film. When a change inresistance caused due to the magneto-resistance effect is sensed by thissense current, magnetic field from Medium is sensed. As the lowerelectrode 21, a metal layer whose electric resistance is relativelysmall is employed to feed a current to the magnetoresistive film.

As the under layer 11, a film made of Ta [5 nm]/Ru [2 nm] is formed onthe lower electrode 21. Ta layer is a buffer layer that lessens aroughness of the lower electrode. Ru layer is a seed layer that controlsthe crystal orientation and the crystal particle size of the spin valvefilm formed thereon.

As the buffer layer, Ti, Zr, Hf, V, Cr, Mo, W or their alloy materialmay be employed instead of Ta. It is desirable that a film thickness ofthe buffer layer should be set to 1 nm to 5 nm. When the buffer layer istoo thin, a buffer effect is lost. In contrast, when the buffer layer istoo thick, an increase in the series resistance is caused undesirablywhen a sense current is fed in the perpendicular direction.

As the seed layer, preferably a material having an hcp structure(hexagonal close-packed structure) or an fcc structure (face-centeredcubic structure) should be employed.

When Ru is employed as the seed layer, the crystal orientation of thespin valve film formed thereon can be set to fcc (111) orientation, thecrystal orientation of PtMn can be set to fct (111) orientation, and thecrystal orientation of the bcc structure can be set to bcc (110)orientation.

It is preferable that a film thickness of the seed layer should be setto 2 to 6 nm. When a thickness of the seed layer is too thin, an effectof controlling the crystal orientation is lost. In contrast, when theseed layer is too thick, an increase in the series resistance is causedundesirably when a sense current is fed in the perpendicular direction.

As the pinning layer 12, Pt₅₀Mn₅₀ [15 nm] is formed on the under layer11. The pinning layer 12 has a function of pinning the magnetizationdirection of the pin layer 13 formed thereon. A too thin film thicknessof the pinning layer 12 is not preferable because the pinning layer 12does not carry out a magnetization pinning function, while a too thickfilm thickness of the pinning layer 12 is not preferable from aviewpoint of the narrower gap. When Pt50Mn50 is used as the pinninglayer 12, a film thickness of Pt₅₀Mn₅₀ should be set preferably to about8 nm to 20 nm, more preferably to 10 nm to 15 nm.

As the antiferromagnetic material used as the pinning layer 12, PdPtMn,IrMn may be listed in addition to PtMn. Since IrMn fulfills themagnetization pinning function at a thinner film thickness than PtMn orPdPtMn, such IrMn is desirable from a viewpoint of the narrower gap.When IrMn is used as the pinning layer 12, a film thickness of IrMnshould be set preferably to 4 nm to 12 nm, more preferably to 5 nm to 10nm.

The pin layer 13 is formed on the pinning layer 12. In first example, asynthetic pin layer composed of a lower pin layer 131 (Co₉₀Fe₁₀ [1 nm to3 nm]), a magnetic coupling intermediate layer 132 (Ru [0.9 nm]), andthe upper pin layer 133 (magnetic compound M1-M2-X) is employed as thepin layer 13.

The lower pin layer 131 is coupled to the pinning layer 12 viaexchange-magnetic coupling, and has unidirectional anisotropy. The lowerpin layer 131 and the upper pin layer 133 are magnetically coupled toeach other via the magnetic coupling intermediate layer 132 such thattheir magnetization directions are set in inverse parallel with eachother.

In the first example, the material of the magnetic compound M1-M2-X usedas the upper pin layer 133 is formed by using Co as the magnetic metalelement M1, Ti as the nonmagnetic metal element M2, and O as thenonmetal element X while changing a composition ratio.

Preferably the lower pin layer 131 should be designed such that amagnetic film thickness, i.e., (saturation magnetization Bs)×(filmthickness t) (which is Bs·t product) is set almost equal to the upperpin layer 133. In the first example, a film thickness of the magneticcompound (Co—Ti—O) used as the upper pin layer 133 is fixed to 3 nm, anda film thickness of Co₉₀Fe₁₀ used as the lower pin layer 131 wasadjusted appropriately within 1 nm to 3 nm such that the saturationmagnetization of Co₉₀Fe₁₀ used as the lower pin layer 131 becomes equalto the magnetic film thickness of the upper pin layer 133.

From viewpoints of the unidirectional anisotropic magnetic fieldstrength by the pinning layer 12 (PtMn) and the antiferromagneticcoupled magnetic field strength between the lower pin layer 131 and theupper pin layer 133 via Ru, preferably a film thickness of the magneticlayer used as the lower pin layer 131 should be set to about 0.5 nm to 5nm. When a film thickness is too thin, an MR ratio is reduced. When afilm thickness is too thick, it is difficult to obtain the sufficientunidirectional anisotropic magnetic field necessary for the deviceoperation.

As the lower pin layer 131, for example, a Co_(x)Fe_(100-x) alloy (x=0to 100), an Ni_(x)Fe_(100-x) alloy (x=0 to 100), or an alloy obtained byadding to a nonmagnetic element the above alloy can be employed.

The magnetic coupling intermediate layer (Ru layer) 132 has a functionof forming a synthetic pin structure by causing the antiferromagneticcoupling in the upper and lower magnetic layers. It is preferable that afilm thickness of the magnetic coupling intermediate layer 132 should beset to 0.8 nm to 1 nm. Any material except Ru may be employed if suchmaterial can cause the enough antiferromagnetic coupling in the upperand lower magnetic layers.

The upper pin layer 133 constitutes a part of the spin-dependentscattering unit. In particular, the magnetic material locating at theinterface to the spacer 16 is important in contributing to thespin-dependent interfacial scattering. In present Example, Co—Ti—O [3nm] is formed as the magnetic compound M1-M2-X while changing acomposition ratio. The upper pin layer 133 containing such magneticcompound Co—Ti—O as a main component has a high spin-dependentscattering effect.

As the spacer layer 14, Cu [5 nm] is formed on the pin layer 13. As thespacer layer 14, Au, Ag, or the like may be employed in place of Cu. Itis desirable that a film thickness of the spacer layer 14 should be setthicker to break the magnetic coupling between the free layer and thepin layer, and should be set to a spin scattering length or less.Therefore, the film thickness of the spacer layer should be setpreferably to 0.5 nm to 10 nm, more preferably to 1.5 nm to 5 nm.

As the free layer 15, the magnetic compound Co—Ti—O [3 nm] is formed onthe spacer layer 14 while changing a composition ratio. The free layer15 having such magnetic compound Co—Ti—O as a main component has a highspin-dependent scattering effect.

As the cap layer, Cu [1 nm]/Ta [5 nm] is formed on the free layer 15.

The magnetoresistive elements according to the first example are formedby using the magnetic compound Co—Ti—O [3 nm] as the upper pin layer 133and the free layer 15 while changing a composition ratio of Co—Ti—O.Also, as a comparative example, the magneto-resistive elements areformed by using the conventional material Co₉₀Fe₁₀ [3 nm] as the upperpin layer 133 and the free layer 15.

As a method of forming the magnetic compound layer in the first example,a method of forming a film made of the M1-M2 alloy material by thesputter and causing it to react in an X element atmosphere was employed.The magnetic compound layer M1-M2-X may be formed by stacking films ofthe pure M1 material and the pure M2 material by the sputter and thencausing them to react in the X element atmosphere. These films may becaused to react in the X element atmosphere while irradiating the ionbeam of a rare gas such as Ar, or the like or the plasma simultaneously.According to this method, the stable magnetic compound can be formed.Also, the films may be formed by the sputter while using an M1-M2-Otarget.

In the first example, the magnetoresistive elements having thecomposition ratio given in the composition formula expressed byCo_(a)Ti_(b)O_(c) shown in following Table 1 are manufactured. (Here,“c” are an atomic percent [at %].) In Table 1, remarks indicatingwhether the MR ratio is improved in each composition rather than thecomparative example or not is shown together.

TABLE 1 Improvement in MR ratio sample No. Magnetic Material toComparative Example (Comp. Example) Co₉₀Fe₁₀ — A00 A01 Co₆₉Ti₁₀O₂₁ notimproved A02 Co₆₈Ti₁₀O₂₂ improved A03 Co₆₀Ti₁₀O₃₀ particularly improvedA04 Co₄₀Ti₁₀O₅₀ particularly improved A05 Co₁₅Ti₁₀O₇₅ particularlyimproved A06 Co₅Ti₁₀O₈₅ improved A07 Co₄Ti₁₀O₈₆ not improved A08Co₆₉Ti₉O₂₂ not improved A09 Co₅Ti₇₃O₂₂ improved A10 Co₄Ti₇₄O₂₂ notimproved A11 Co₄Ti₆₆O₃₀ not improved A12 Co₄Ti₃₀O₆₆ not improved A13Co₅Ti₆₅O₃₀ particularly improved A14 Co₁₀Ti₅₀O₄₀ particularly improvedA15 Co₃₀Ti₃₀O₄₀ particularly improved A16 Co₂₀Ti₂₀O₆₀ particularlyimproved

When the magnetoresistive element of the first example was evaluated, itwas confirmed that the MR ratio higher than that in the ComparativeExample was obtained by the magnetoresistive element that wasmanufactured at the Co—Ti—O composition ratio in a particular range. Thereason for such improvement in the MR ratio can be considered such thatthe magnetic compound has a high spin polarizability by attaining aproper composition ratio. The reason why the magnetic compound accordingto the present invention has the high spin polarizability may beconsidered as follows. Since the non-magnetic 3d transition metalelement has the electronic structure similar to that of the magnetic 3dtransition metal element, such metal element is ready to have a weakmagnetism. When the non-magnetic 3d transition metal element and themagnetic 3d transition metal element are bonded together, their bandstructures are changed mutually and thus a magnetism of the non-magnetic3d transition metal element appears more conspicuously. Therefore, notonly the magnetic 3d transition metal element but also the non-magnetic3d transition metal element contributes to the spin-dependentconduction. Also, when the nonmetallic element is bonded to the abovemetallic element, a change in band structure of the non-magnetic 3dtransition metal element and the magnetic 3d transition metal elementcan be encouraged. As a result, the band structures of the non-magnetic3d transition metal element and the magnetic 3d transition metal elementnear the Fermi surface are changed, and the high spin polarizability canbe obtained.

The MR ratio of the comparative example A00 is 0.6%. It is confirmedthat the magnetoresistive element manufactured in ranges of 5≦a≦68, and22≦c≦85 has the MR ratio of 1% or more, which exceeds the comparativeexample. Also, the particularly high MR ratio in excess of 15% wasconfirmed in the magnetoresistive element manufactured in the range of30≦c≦75 among the above ranges. Thus, improvement in the MR ratio due touse of the magnetic compound was particularly remarkably noticed.

When an added amount of a composition ratio “b” of the non-magnetic 3dtransition metal element Ti, V, Cr, Mn is too small in the magneticcompound expressed by the formula M1_(a)M2_(b)X_(c), a contribution ofthe non-magnetic 3d transition metal element to the spin-dependentconduction is reduced. Therefore, it is preferable that the compositionratio “b” should be set to 10≦b. However, when an added amount is toolarge, the magnetic 3d transition metal element is reduced relatively,and the bonding between the non-magnetic 3d transition metal element andthe magnetic 3d transition metal element is reduced. Thus, a magnetismof the non-magnetic 3d transition metal element is weakened. Therefore,it is more preferable that the composition ratio “b” should be set to10≦b≦73.

In order to obtain an effect of encouraging a change of the bandstructures of the non-magnetic 3d transition metal element and themagnetic 3d transition metal element, preferably a composition ratio “c”of the nonmetallic element N, O, C in the magnetic compound expressed bythe formula M1_(a)M2_(b)X_(c) should be set to 22≦c. However, when anadded amount is too large, the non-magnetic 3d transition metal elementand the magnetic 3d transition metal element are reduced relatively, andthen an amount of elements to bear the spin-dependent conduction isreduced. Therefore, it is desirable that the composition ratio “c”should be set to 22≦c≦85. In addition, in order to obtain the large spinpolarizability in a situation that this element is bonded to most of theelements contained in the non-magnetic 3d transition metal element andthe magnetic 3d transition metal element, the particularly high MR ratiocan be obtained when the composition ratio “c” should be set to 30≦c≦75.

When an added amount of a composition ratio “a” of the magnetic 3dtransition metal element Co, Fe, Ni is too small in the magneticcompound expressed by the formula M1_(a)M2_(b)X_(c), the bonding betweenthe non-magnetic 3d transition metal element and the magnetic 3dtransition metal element is reduced. Thus, a magnetism of thenon-magnetic 3d transition metal element is weakened. However, when anadded amount is too large, the composition ratio “b” of the non-magnetic3d transition metal element and the composition ratio “c” of thenonmetallic element are reduced relatively, and then an effect ofincreasing the spin polarizability due to the addition of thenon-magnetic 3d transition metal element and the nonmetallic element, asalready described, is weakened. Therefore, it is more desirable that thecomposition ratio “a” should be set to 5≦a≦68.

As the crystal structure of the magnetic compound, sometimes suchcrystal structure is amorphous in a composition range of the formulaM1_(a)M2_(b)X_(c), especially a composition range of 30≦c≦75 withinwhich the MR ratio is high. Since the spin-dependent scattering surfacebecomes smooth when the crystal structure becomes amorphous, thespin-dependent scattering effect is further enhanced and accordingly ahigher MR ratio can be obtained.

As a film thickness of the layer in which the magnetic compoundexpressed by the formula M1_(a)M2_(b)X_(c) is contained, it is desirablethat the film thickness should be thinned, particularly should be set to5 nm or less, from a viewpoint that a gap length of the spin valve filmis shortened and a viewpoint that a resistance value is increasedunnecessarily. In contrast, since the sufficient spin-dependentscattering effect cannot be obtained when the film thickness is thinnedexcessively, it is desirable that the film thickness should be set to0.5 nm or more. From the above, it is desirable that the film thicknessof the magnetic compound should be set to 0.5 nm or more but 5 nm orless. In present Example, a film thickness of the magnetic compoundlayer was set to 3 nm.

In the first example, the magnetic compound Co—Ti—O was used as theupper pin layer 133 and the free layer 15. In this case, the magneticcompound Co—Ti—O may be used as any one of the upper pin layer 133 andthe free layer 15, and the conventional material may be used as theother layer. Since the spin-dependent scattering of the inserted layeris increased even when the magnetic compound is inserted into only onelayer, the MR ratio can be improved.

In case the magnetic compound Co—Ti—O is used as the upper pin layer 133and the conventional material is used as the free layer 15, Co₉₀Fe₁₀ [1nm]/Ni₈₃Fe₁₇ [3.5 nm], for example, can be used as the free layer 15. Inorder to obtain the high MR ratio when the conventional material isused, the selection of the magnetic material of the free layer 15located on the interface to the spacer layer 14 is important. In thiscase, preferably a CoFe alloy should be provided to the interface to thespacer layer 14 rather than a NiFe alloy. When the CoFe alloy isemployed in vicinity of Co₉₀Fe₁₀, preferably a film thickness of thisalloy should be set to 0.5 nm to 4 nm. When the CoFe alloy having othercomposition (for example, the composition explained in connection withthe pin layer 13) is employed, preferably the film thickness should beset to 0.5 nm to 2 nm. For example, in order to increase thespin-dependent interface scattering effect, such a case maybe consideredthat Fe₅₀Co₅₀ (or Fe_(x)Co_(100-x) (x=45 to 85)) having the bccstructure is used as the free layer 15. In this case, a too thick filmthickness cannot be used as the free layer 15 to maintain the softmagnetism, and therefore 0.5 nm to 1 nm gives a preferable filmthickness range.

Since the soft magnetic characteristic is relatively good when Fe notcontaining Co is used, a film thickness can be set to about 0.5 nm to 4nm.

A NiFe layer provided on the CoFe layer is the material whose softmagnetic characteristic is stable. The soft magnetic characteristic ofthe CoFe alloy is not so stable. However, the soft magneticcharacteristic can be complemented by providing the NiFe alloy thereon,and the high MR ratio can be obtained.

It is preferable that a composition of the NiFe alloy should be set toNi_(x)Fe_(100-x) (x=about 78 to 85). It is preferable that a filmthickness of the NiFe layer should be set to about 2 nm to 5 nm.

When the NiFe layer is not used, the free layer 15 constructed bystacking a CoFe layer or an Fe layer of 1 nm to 2 nm thick and a verythin Cu layer of about 0.1 to 0.8 nm thick in plural alternately may beemployed.

When the magnetic compound layer Co—Ti—O is used as the free layer 15and the conventional material is used as the upper pin layer 133,{(Fe₅₀Co₅₀ [1 nm]/Cu [2.5 nm])×2/Fe₅₀Co₅₀ [1 nm]}, for example, can beused as the upper pin layer 133. Out of the conventional materials, whenthe magnetic material having the bcc structure on the interface to thespacer layer 14 is used, the high MR ratio can be realized because suchmaterial has the high spin-dependent interface scattering effect. As aFeCo-based alloy having the bcc structure, Fe_(x)Co_(100-x) (x=30 to100) and an alloy obtained by adding an addition element toFe_(x)Co_(100-x) are listed. Also, when the upper pin layer 133 isformed by the magnetic layer having the bcc structure that is ready toattain the high MR ratio, preferably a film thickness of the layerhaving the bcc structure should be set to 2 nm or more to keep the bccstructure more stably. In order to obtain the strong magnetizationpinning magnetic field and keep a stability of the bcc structure,preferably a film thickness range of the upper pin layer 133 having thebcc structure should be set to about 2.5 nm to 4 nm.

As the upper pin layer 133, the layer obtained by stacking a magneticlayer (FeCo layer) and a nonmagnetic layer (very thin Cu layer)alternately can be employed. In the upper pin layer 133 having suchstructure, the spin-dependent scattering effect called the bulkscattering effect can be improved.

As the upper pin layer 133, a single-layer film made of Co, Fe, Ni, ortheir alloy material may be employed. For example, as the upper pinlayer 133 having the simplest structure, a Co90Fe10 single layer may beemployed. An element may be added to such material.

First Variation: a Single Spin Valve

As a first variation of the first example shown in FIG. 1, amagneto-resistive element whose magnetization pinning layer is formed bynot a three-layered structure (synthetic structure) but a single layeris shown in FIG. 2.

As shown in FIG. 2, the magnetoresistive element according to the firstvariation includes the lower electrode 21, the under layer 11, thepinning layer 12, the pin layer 13, the spacer layer 14, the free layer15, the cap layer 16, and the upper electrode 22, which are formedsequentially from the bottom on the substrate.

In the first variation, the magnetic compound M1-M2-X is employed as thesingle pin layer 13 and the free layer 15.

Similar to the first example, Co—Ti—O can be employed as the magneticcompound M1-M2-X. In the first variation, the similar advantages tothose in first example can be obtained. As for the compositions in themagnetic compound M1-M2-X, even when at least one type of magnetic 3dtransition metal elements selected from Co, Fe, Ni is employed as M1,the similar advantages can be obtained. Even when at least one type ofnon-magnetic 3d transition metal elements selected from Ti, V, Cr, Mn isemployed as M2, the similar advantages can be obtained. Even when atleast one type of nonmetallic elements selected from N, O, C is employedas X, the similar advantages can be obtained.

Second Variation: a Top Type Spin Valve

As a second variation of first example shown in FIG. 1, amagnetoresistive element in which the magnetization pin layer and themagnetization free layer are positioned via the spacer layer converselyto the first example is shown in FIG. 3.

As shown in FIG. 3, the magnetoresistive element of the second variationincludes the lower electrode 21, the under layer 11, the free layer 15,the spacer layer 14, the pin layer 13, the pinning layer 12, the caplayer 16, and the upper electrode 22, which are formed sequentially fromthe bottom on the substrate.

In the second variation, a synthetic spin valve structure is employed,and the magnetic compound M1-M2-X is employed as the lower pin layer 133of the pin layer 13 located on the spacer side and the free layer 15.

Similar to the first example, Co—Ti—O can be employed as the magneticcompound M1-M2-X. In the second variation, the similar advantages tothose in the first example can be obtained. As for the compositions inthe magnetic compound M1-M2-X, even when at least one type of magnetic3d transition metal elements selected from Co, Fe, Ni is employed as M1,the similar advantages can be obtained. Even when at least one type ofnon-magnetic 3d transition metal elements selected from Ti, V, Cr, Mn isemployed as M2, the similar advantages can be obtained. Even when atleast one type of nonmetallic elements selected from N, O, C is employedas X, the similar advantages can be obtained.

Third Variation: a Dual Pin Type Spin Valve

As a third variation of the first example shown in FIG. 1, a dual typemagnetoresistive element in which the spacer layer and the pin layer areprovided on and under the free layer respectively is shown in FIG. 4.

As shown in FIG. 4, the magnetoresistive element of the third variationincludes the lower electrode 21, the under layer 11, the pinning layer12, the pin layer 13, the spacer layer 14, the free layer 15, a spacerlayer 17, a pin layer 18, a pinning layer 19, the cap layer 16, and theupper electrode 22, which are formed sequentially from the bottom on thesubstrate.

In the third variation, a synthetic structure is employed as the pinlayer 13 and the pin layer 18, and the magnetic compound M1-M2-X isemployed as the upper pin layer 133 of the pin layer 13 located on thespacer side, a lower pin layer 183 of the pin layer 18 located on thespacer side, and the free layer 15. Pin layer 18 also includes anintermediate layer 182 and an upper pin layer 181.

Similar to the first example, Co—Ti—O can be employed as the magneticcompound M1-M2-X. In the third variation, the similar advantages tothose in first example can be obtained. As for the compositions in themagnetic compound M1-M2-X, even when at least one type of magnetic 3dtransition metal elements selected from Co, Fe, Ni is employed as M1,the similar advantages can be obtained. Even when at least one type ofnon-magnetic 3d transition metal elements selected from Ti, V, Cr, Mn isemployed as M2, the similar advantages can be obtained. Even when atleast one type of nonmetallic elements selected from N, O, C is employedas X, the similar advantages can be obtained.

Fourth Variation: Stacked Free Layer Structure

As a fourth variation of the first example shown in FIG. 1, amagneto-resistive element in which a stacked structure composed of amagnetic compound layer and a ferromagnetic thin film layer is used asthe free layer is shown in FIG. 5.

As shown in FIG. 5, a magnetoresistive element of the fourth variationincludes the lower electrode 21, the under layer 11, the pinning layer12, the pin layer 13, the spacer layer 14, the free layer 15, the caplayer 16, and the upper electrode 22, which are formed sequentially fromthe bottom on the substrate. In the fourth variation, the free layer 15is formed of a stacked film composed of a lower free layer 151 and anupper free layer 152. Also, in the fourth variation, the synthetic spinvalve structure is employed, and the magnetic compound layer M1-M2-X isemployed as the upper pin layer 133 of the pin layer 13 located on thespacer side and the lower free layer 151.

When a soft magnetic film that is superior in the soft magneticcharacteristic to the magnetic compound layer is employed as theferromagnetic thin film layer used as the upper free layer 152, amagnetic field responsibility can be improved. A NiFe alloy can beemployed as the material of the ferromagnetic thin film layer used asthe upper free layer 152. Ni_(x)Fe_(100-x) (x=about 78 to 85) ispreferable as the composition of the NiFe alloy, and about 2 nm to 5 nmis preferable as a film thickness of the NiFe layer. When the NiFe layeris not employed, a configuration may be employed in which the free layerobtained by stacking a CoFe layer or a Fe layer of 1 nm to 2 nmthickness and a very thin Cu layer of about 0.1 nm to 0.8 nm thicknessin plural alternately. Also, Co₉₀Fe₁₀ whose soft magnetic characteristicis particularly stable out of the CoFe alloy may be employed. When theCoFe alloy similar to Co₉₀Fe₁₀ is employed, preferably a film thicknessshould be set to 0.5 nm to 4 nm. When the CoFe alloy having othercomposition is employed, preferably a film thickness should be set to0.5 nm to 2 nm to maintain the soft magnetic characteristic.

Similar to the first example, Co—Ti—O can be employed as the magneticcompound M1-M2-X. In the fourth variation, the higher MR ratio than theconventional material can be obtained similarly to first example. As forthe compositions in the magnetic compound M1-M2-X, even when at leastone type of magnetic 3d transition metal elements selected from Co, Fe,Ni is employed as M1, the similar advantages can be obtained. Even whenat least one type of non-magnetic 3d transition metal elements selectedfrom Ti, V, Cr, Mn is employed as M2, the similar advantages can beobtained. Even when at least one type of nonmetallic elements selectedfrom N, O, C is employed as X, the similar advantages can be obtained.

In the fourth example, the magnetic compound layer M1-M2-X is employedas the lower free layer 151 and the ferromagnetic thin film layer isemployed as the upper free layer 152. But the ferromagnetic thin filmlayer may be employed as the lower free layer 151 and the magneticcompound layer M1-M2-X may be employed as the upper free layer 152. Incase the spin-dependent scattering of the magnetic compound isconsidered separately as the bulk scattering and the interfacescattering, sometimes such a situation is caused depending on the methodof manufacturing the magnetic compound layer M1-M2-X that thespin-dependent bulk scattering becomes higher than the conventionalferromagnetic material used as the ferromagnetic thin film layer and thespin-dependent interface scattering becomes lower than the conventionalferromagnetic material used as the ferromagnetic thin film layer. Insuch case, only the spin-dependent bulk scattering effect of themagnetic compound layer is used effectively by arranging theferromagnetic thin film layer on the spacer layer interface, so that thehigh MR ratio can be obtained. Also, in the fourth example, thetwo-layered stacked structure composed of the magnetic compound layerand the ferromagnetic thin film layer is employed, but a three-layeredstacked structure composed of the ferromagnetic thin film layer/magneticcompound layer/ferromagnetic thin film layer, or the like may beemployed.

In the fourth example, a single layer of the magnetic compound M1-M2-Xis employed as the pin layer, but the conventional material may beemployed. Also, in combination with fifth variation described hereunder,both magnetic layers of the free layer and the pin layer may of thestacked type.

Fifth Variation: Stacked Pin Layer Structure

As a fifth variation of the first example shown in FIG. 1, amagnetoresistive element in which a stacked structure composed of themagnetic compound layer and the ferromagnetic thin film layer is used asthe pin layer is shown in FIG. 6.

As shown in FIG. 6, the magnetoresistive element of the fifth variationincludes the lower electrode 21, the under layer 11, the pinning layer12, the pin layer 13, the spacer layer 14, the free layer 15, the caplayer 16, and the upper electrode 22, which are formed sequentially fromthe bottom on the substrate. In present fifth variation, the syntheticspin valve structure is employed, and a stacked film composed of anupper pin layer lower layer 1331 and an upper pin layer upper layer 1332is employed as the upper pin layer 133 of the pin layer 13 located onthe spacer side and the magnetic compound expressed by the formulaM1_(a)M2_(b)X_(c) is employed as the upper pin layer upper layer 1332and the free layer 15.

According to the fifth variation, because the pin layer is easily pinnedin one direction by employing the stacked structure composed of themagnetic compound layer and the ferromagnetic layer as the upper pinlayer 133, the pin characteristic of the pin layer can be improved. Inpresent Variation, the ferromagnetic layer is used as the upper pinlayer lower layer 1331. As the material of the ferromagnetic thin filmlayer used as the upper pin layer lower layer 1331, a single metal ofCo, Fe, Ni, or the like, or all the alloy materials containing any oneof these elements can be employed.

Similar to the first example, Co—Ti—O can be employed as the magneticcompound M1-M2-X. In the fifth variation, the higher MR ratio than theconventional material can be obtained like first example. As for thecompositions in the magnetic compound M1-M2-X, even when at least onetype of magnetic 3d transition metal elements selected from Co, Fe, Niis employed as M1, the similar advantages can be obtained. Even when atleast one type of non-magnetic 3d transition metal elements selectedfrom Ti, V, Cr, Mn is employed as M2, the similar advantages can beobtained. Even when at least one type of nonmetallic elements selectedfrom N, O, C is employed as X, the similar advantages can be obtained.

In the fifth example, the magnetic compound layer M1-M2-X is employed asthe upper pin layer upper layer 1332 and the ferromagnetic thin filmlayer is employed as the upper pin layer lower layer 1331. But theferromagnetic thin film layer may be employed as the upper pin layerupper layer 1332 and the magnetic compound layer may be employed as theupper pin layer lower layer 1331. In case the spin-dependent scatteringof the magnetic compound is considered separately as the bulk scatteringand the interface scattering, in some cases such a situation is causeddepending on the method of manufacturing the magnetic compound layerM1-M2-X that the spin-dependent bulk scattering becomes higher than theconventional ferromagnetic material used as the ferromagnetic thin filmlayer and the spin-dependent interface scattering becomes lower than theconventional ferromagnetic material used as the ferromagnetic thin filmlayer. In such case, only the spin-dependent bulk scattering effect ofthe magnetic compound layer is utilized effectively by arranging theferromagnetic thin film layer on the spacer layer interface, so that thehigh MR ratio can be obtained. Also, in present fifth example, thetwo-layered stacked structure composed of the magnetic compound layerand the ferromagnetic thin film layer is employed, but a three-layeredstacked structure composed of the ferromagnetic thin film layer/magneticcompound layer/ferromagnetic thin film layer, or the like may beemployed.

In the fifth example, a single layer of the magnetic compound layerM1-M2-X is employed as the free layer, but the conventional material maybe employed. Also, both magnetic layers of the free layer and the pinlayer may have the stacked structure composed of the magnetic compoundlayer and the ferromagnetic thin film layer, in combination with fifthvariation described hereunder.

SECOND EXAMPLE

Next, a magnetoresistive element of a second example according to theembodiment of the present invention will be explained hereunder. Thesecond example is different from the first example in that the materialof the magnetic compound is varied. Therefore, explanation of theportions different apparently from first example will be made hereunder,but explanation of the similar portions will be omitted herein.

The magnetoresistive elements according to the second example aremanufactured by using the magnetic compound Co—V—O [3 nm] as the upperpin layer 133 and the free layer 15 while changing a composition ratioof Co—V—O. Also, as a comparative example, the magnetoresistive elementin which the conventional material Co₉₀Fe₁₀ [3 nm] is used as the upperpin layer 133 and the free layer 15 is also manufactured.

When the magnetoresistive element of the second example is evaluated, itis confirmed that the MR ratio higher than that in the ComparativeExample was obtained by the magnetoresistive element that wasmanufactured at the Co—V—O composition ratio in a particular range. Thereason for such improvement in the MR ratio can be considered such thatthe magnetic compound has the high spin polarizability by attaining aproper composition ratio

In the second example, the magnetoresistive elements having thecomposition ratio given in the composition formula expressed byCo_(a)V_(b)O_(c) as shown in following Table 2 are manufactured. (Here,“a”, “b”, “c” are an atomic percent [at %].) In Table 2, remarksindicating whether the MR ratio is improved in each composition ratherthan the comparative example or not is shown together.

TABLE 2 Improvement in MR ratio sample No. Magnetic Material toComparative Example (Comp. Example) Co₉₀Fe₁₀ — A00 B01 Co₆₉V₁₀O₂₁ notimproved B02 Co₆₈V₁₀O₂₂ improved B03 Co₆₀V₁₀O₃₀ particularly improvedB04 Co₄₀V₁₀O₅₀ particularly improved B05 Co₁₅V₁₀O₇₅ particularlyimproved B06 Co₅V₁₀O₈₅ improved B07 Co₄V₁₀O₈₆ not improved B08 Co₆₉V₉O₂₂not improved B09 Co₅V₇₃O₂₂ improved B10 Co₄V₇₄O₂₂ not improved B11Co₄V₆₆O₃₀ not improved B12 Co₄V₃₀O₆₆ not improved B13 Co₅V₆₅O₃₀particularly improved B14 Co₁₀V₅₀O₄₀ particularly improved B15Co₃₀V₃₀O₄₀ particularly improved B16 Co₂₀V₂₀O₆₀ particularly improved

The MR ratio of the comparative example A00 is 0.6%. It is confirmedthat the magnetoresistive element manufactured in ranges of 5≦a≦68,10≦b≦73, and 22≦c≦85 has the MR ratio of 1% or more, which exceedsComparative Example. Also, the particularly high MR ratio in excess of15% was confirmed in the magnetoresistive element manufactured in therange of 30≦c≦75 among the above ranges. Thus, improvement in the MRratio due to use of the magnetic compound was particularly remarkablynoticed. When an added amount of a composition ratio “b” of thenon-magnetic 3d transition metal element Ti, V, Cr, Mn is too small inthe magnetic compound expressed by the formula M1_(a)M2_(b)X_(c), acontribution of the non-magnetic 3d transition metal element to thespin-dependent conduction is reduced. Therefore, it is preferable thatthe composition ratio “b” should be set to 10≦b. However, when an addedamount is too large, the magnetic 3d transition metal element is reducedrelatively, and the bonding between the non-magnetic 3d transition metalelement and the magnetic 3d transition metal element is reduced. Thus, amagnetism of the non-magnetic 3d transition metal element is weakened.Therefore, it is more preferable that the composition ratio “b” shouldbe set to 10≦b≦73.

In order to obtain an effect of encouraging a change of the bandstructures of the non-magnetic 3d transition metal element and themagnetic 3d transition metal element, preferably a composition ratio “c”of the nonmetallic element N, O, C in the magnetic compound expressed bythe formula M1_(a)M2_(b)X_(c) should be set to 22≦c. However, when anadded amount is too large, the non-magnetic 3d transition metal elementand the magnetic 3d transition metal element are reduced relatively, andthen an amount of elements to bear the spin-dependent conduction isreduced. Therefore, it is desirable that the composition ratio “c”should be set to 22≦c≦85. In addition, in order to obtain the large spinpolarizability in a situation that this element is bonded to most of theelements contained in the non-magnetic 3d transition metal element andthe magnetic 3d transition metal element, the particularly high MR ratiocan be obtained when the composition ratio “c” should be set to 30≦c≦75.

When an added amount of a composition ratio “a” of the magnetic 3dtransition metal element Co, Fe, Ni is too small in the magneticcompound expressed by the formula M1aM2bXc, the bonding between thenon-magnetic 3d transition metal element and the magnetic 3d transitionmetal element is reduced. Thus, a magnetism of the non-magnetic 3dtransition metal element is weakened. However, when an added amount istoo large, the composition ratio “b” of the non-magnetic 3d transitionmetal element and the composition ratio “c” of the nonmetallic elementare reduced relatively, and then an effect of increasing the spinpolarizability due to the addition of the non-magnetic 3d transitionmetal element and the nonmetallic element, as already described, isweakened. Therefore, it is more desirable that the composition ratio “a”should be set to 5≦a≦68.

In the second example, as for the compositions in the magnetic compoundformula M1_(a)M2_(b)X_(c), Co was employed as M1, V was employed as M2,and O was employed as X. Even when at least one type of magnetic 3dtransition metal elements selected from Co, Fe, Ni is employed as M1,the similar advantages can be obtained. Even when at least one type ofnon-magnetic 3d transition metal elements selected from Ti, V, Cr, Mn isemployed as M2, the similar advantages can be obtained. Even when atleast one type of nonmetallic elements selected from N, O, C is employedas X, the similar advantages can be obtained.

In the second example, variations of the film structure similar to thefirst to fifth variations of the first example can be applied.

THIRD EXAMPLE

Next, a magnetoresistive element of a third example according to theembodiment of the present invention will be explained hereunder. Thethird example is different from the first example in that the materialof the magnetic compound is varied. Therefore, explanation of theportions different apparently from first example will be made hereunder,but explanation of the similar portions will be omitted herein.

In the third example, the magnetoresistive elements are manufactured byusing the magnetic compound Co—Cr—O [3 nm] as the upper pin layer 133and the free layer 15 while changing a composition ratio of Co—Cr—O.Also, as a comparative example, the magnetoresistive element in whichthe conventional material Co₉₀Fe₁₀ [3 nm] is used as the upper pin layer133 and the free layer 15 is also manufactured.

When the magnetoresistive element of the third example was evaluated, itwas confirmed that the MR ratio higher than that in the comparativeexample was obtained by the magnetoresistive element that wasmanufactured at the Co—Cr—O composition ratio in a particular range. Thereason for such improvement in the MR ratio can be considered such thatthe magnetic compound has the high spin polarizability by attaining aproper composition ratio.

In the third example, the magnetoresistive elements having thecomposition ratio given in the composition formula expressed byCo_(a)Cr_(b)O_(c) shown in Table 3 are manufactured. (Here, “a”, “b”,“c” are an atomic percent [at %].) In Table 3, remarks indicatingwhether the MR ratio is improved in each composition rather than thecomparative example or not is shown together.

TABLE 3 Improvement in MR ratio sample No. Magnetic Material toComparative Example (Comp. Example) Co₉₀Fe₁₀ — A00 C01 Co₆₉Cr₁₀O₂₁ notimproved C02 Co₆₈Cr₁₀O₂₂ improved C03 Co₆₀Cr₁₀O₃₀ particularly improvedC04 Co₄₀Cr₁₀O₅₀ particularly improved C05 Co₁₅Cr₁₀O₇₅ particularlyimproved C06 Co₅Cr₁₀O₈₅ improved C07 Co₄Cr₁₀O₈₆ not improved C08Co₆₉Cr₉O₂₂ not improved C09 Co₅Cr₇₃O₂₂ improved C10 Co₄Cr₇₄O₂₂ notimproved C11 Co₄Cr₆₆O₃₀ not improved C12 Co₄Cr₃₀O₆₆ not improved C13Co₅Cr₆₅O₃₀ particularly improved C14 Co₁₀Cr₅₀O₄₀ particularly improvedC15 Co₃₀Cr₃₀O₄₀ particularly improved C16 Co₂₀Cr₂₀O₆₀ particularlyimproved

The MR ratio of the comparative example A00 is 0.6%. It is confirmedthat the magnetoresistive element manufactured in ranges of 5≦a≦68,10≦b≦73, and 22≦c≦85 has the MR ratio of 1% or more, which exceeds thecomparative example. Also, the particularly high MR ratio in excess of15% is confirmed in the magnetoresistive element manufactured in therange of 30≦c≦75 among the above ranges. Thus, improvement in the MRratio due to use of the magnetic compound was particularly remarkablynoticed.

When an added amount of a composition ratio “b” of the non-magnetic 3dtransition metal element Ti, V, Cr, Mn is too small in the magneticcompound expressed by the formula M1_(a)M2_(b)X_(c), a contribution ofthe non-magnetic 3d transition metal element to the spin-dependentconduction is reduced. Therefore, it is preferable that the compositionratio “b” should be set to 10≦b. However, when an added amount is toolarge, the magnetic 3d transition metal element is reduced relatively,and the bonding between the non-magnetic 3d transition metal element andthe magnetic 3d transition metal element is reduced. Thus, a magnetismof the non-magnetic 3d transition metal element is weakened. Therefore,it is more preferable that the composition ratio “b” should be set to10≦b≦73.

In order to obtain an effect of encouraging a change of the bandstructures of the non-magnetic 3d transition metal element and themagnetic 3d transition metal element, preferably a composition ratio “c”of the nonmetallic element N, O, C in the magnetic compound expressed bythe formula M1_(a)M2_(b)X_(c) should be set to 22≦c. However, when anadded amount is too large, the non-magnetic 3d transition metal elementand the magnetic 3d transition metal element are reduced relatively, andthen an amount of elements to bear the spin-dependent conduction isreduced. Therefore, it is desirable that the composition ratio “c”should be set to 22≦c≦85. In addition, in order to obtain the large spinpolarizability in a situation that this element is bonded to most of theelements contained in the non-magnetic 3d transition metal element andthe magnetic 3d transition metal element, the particularly high MR ratiocan be obtained when the composition ratio “c” should be set to 30≦c≦75.

When an added amount of a composition ratio “a” of the magnetic 3dtransition metal element Co, Fe, Ni is too small in the magneticcompound expressed by the formula M1_(a)M2_(b)X_(c), the bonding betweenthe non-magnetic 3d transition metal element and the magnetic 3dtransition metal element is reduced. Thus, a magnetism of thenon-magnetic 3d transition metal element is weakened. However, when anadded amount is too large, the composition ratio “b” of the non-magnetic3d transition metal element and the composition ratio “c” of thenonmetallic element are reduced relatively, and then an effect ofincreasing the spin polarizability due to the addition of thenon-magnetic 3d transition metal element and the nonmetallic element, asalready described, is weakened. Therefore, it is more desirable that thecomposition ratio “a” should be set to 5≦a≦68.

In the third example, as for the compositions in the magnetic compoundformula M1_(a)M2_(b)X_(c), Co was employed as M1, Cr was employed as M2,and O was employed as X. Even when at least one type of magnetic 3dtransition metal elements selected from Co, Fe, Ni is employed as M1,the similar advantages can be obtained. Even when at least one type ofnon-magnetic 3d transition metal elements selected from Ti, V, Cr, Mn isemployed as M2, the similar advantages can be obtained. Even when atleast one type of nonmetallic elements selected from N, O, C is employedas X, the similar advantages can be obtained.

In the third example, the film structure similar to the first to fifthvariations of the first example can be applied.

FOURTH EXAMPLE

Next, a magnetoresistive element of a fourth example according to theembodiment of the present invention will be explained hereunder. Thisfourth example is different from first example in that the material ofthe magnetic compound is varied. Therefore, explanation of the portionsdifferent apparently from first example will be made hereunder, butexplanation of the similar portions will be omitted herein.

In the fourth example, the magnetoresistive elements are manufactured byusing the magnetic compound Co—Mn—O as the upper pin layer 133 and thefree layer 15 while changing a composition ratio of Co—Mn—O. Also, as acomparative example, the magnetoresistive element in which theconventional material Co₉₀Fe₁₀ was used as the upper pin layer 133 andthe free layer 15 is also manufactured.

When the magneto-resistive element of the fourth example is evaluated,it is confirmed that the MR ratio higher than that in the comparativeexample was obtained by the magnetoresistive element that wasmanufactured at the Co—Mn—O composition ratio in a particular range. Thereason for such improvement in the MR ratio can be considered such thatthe magnetic compound has the high spin polarizability by attaining aproper composition ratio.

In the fourth example, the magnetoresistive elements having thecomposition ratio given in the composition formula expressed byCo_(a)Mn_(b)O_(c) shown in following Table 4 are manufactured. (Here,“a”, “b”, “c” are an atomic percent [at %].) In Table 4, remarksindicating whether the MR ratio is improved in each composition ratherthan the comparative example or not are shown together.

TABLE 4 Improvement in MR ratio sample No. Magnetic Material toComparative Example (Comp. Example) Co₉₀Fe₁₀ — A00 D01 Co₆₉Mn₁₀O₂₁ notimproved D02 Co₆₈Mn₁₀O₂₂ improved D03 Co₆₀Mn₁₀O₃₀ particularly improvedD04 Co₄₀Mn₁₀O₅₀ particularly improved D05 Co₁₅Mn₁₀O₇₅ particularlyimproved D06 Co₅Mn₁₀O₈₅ improved D07 Co₄Mn₁₀O₈₆ not improved D08Co₆₉Mn₉O₂₂ not improved D09 Co₅Mn₇₃O₂₂ improved D10 Co₄Mn₇₄O₂₂ notimproved D11 Co₄Mn₆₆O₃₀ not improved D12 Co₄Mn₃₀O₆₆ not improved D13Co₅Mn₆₅O₃₀ particularly improved D14 Co₁₀Mn₅₀O₄₀ particularly improvedD15 Co₃₀Mn₃₀O₄₀ particularly improved D16 Co₂₀Mn₂₀O₆₀ particularlyimproved

The MR ratio of the comparative example A00 is 0.6%. It is confirmedthat the magnetoresistive element manufactured in ranges of 5≦a≦68,10≦b≦73, and 22≦c≦85 has the MR ratio of 1% or more, which exceeds thecomparative example. Also, the particularly high MR ratio in excess of15% was confirmed in the magnetoresistive element manufactured in therange of 30≦c≦75 among the above ranges. Thus, improvement in the MRratio due to use of the magnetic compound is particularly remarkablynoticed.

When an added amount of a composition ratio “b” of the non-magnetic 3dtransition metal element Ti, V, Cr, Mn is too small in the magneticcompound expressed by the formula M1_(a)M2_(b)X_(c), a contribution ofthe non-magnetic 3d transition metal element to the spin-dependentconduction is reduced. Therefore, it is preferable that the compositionratio “b” should be set to 10≦b. However, when an added amount is toolarge, the magnetic 3d transition metal element is reduced relatively,and the bonding between the non-magnetic 3d transition metal element andthe magnetic 3d transition metal element is reduced. Thus, a magnetismof the non-magnetic 3d transition metal element is weakened. Therefore,it is more preferable that the composition ratio “b” should be set to10≦b≦73.

In order to obtain an effect of encouraging a change of the bandstructures of the non-magnetic 3d transition metal element and themagnetic 3d transition metal element, preferably a composition ratio “c”of the nonmetallic element N, O, C in the magnetic compound expressed bythe formula M1_(a)M2_(b)X_(c) should be set to 22≦c. However, when anadded amount is too large, the non-magnetic 3d transition metal elementand the magnetic 3d transition metal element are reduced relatively, andthen an amount of elements to bear the spin-dependent conduction isreduced. Therefore, it is desirable that the composition ratio “c”should be set to 22≦c≦85. In addition, in order to obtain the large spinpolarizability in a situation that this element is bonded to most of theelements contained in the non-magnetic 3d transition metal element andthe magnetic 3d transition metal element, the particularly high MR ratiocan be obtained when the composition ratio “c” should be set to 30≦c≦75.

When an added amount of a composition ratio “a” of the magnetic 3dtransition metal element Co, Fe, Ni is too small in the magneticcompound expressed by the formula M1_(a)M2_(b)X_(c), the bonding betweenthe non-magnetic 3d transition metal element and the magnetic 3dtransition metal element is reduced. Thus, a magnetism of thenon-magnetic 3d transition metal element is weakened. However, when anadded amount is too large, the composition ratio “b” of the non-magnetic3d transition metal element and the composition ratio “c” of thenonmetallic element are reduced relatively, and then an effect ofincreasing the spin polarizability due to the addition of thenon-magnetic 3d transition metal element and the nonmetallic element, asalready described, is weakened. Therefore, it is more desirable that thecomposition ratio “a” should be set to 5≦a≦68.

In the fourth example, as for the compositions in the magnetic compoundformula M1_(a)M2_(b)X_(c), Co is employed as M1, Cr is employed as M2,and O is employed as X. Even when at least one type of magnetic 3dtransition metal elements selected from Co, Fe, Ni is employed as M1,the similar advantages can be obtained. Even when at least one type ofnon-magnetic 3d transition metal elements selected from Ti, V, Cr, Mn isemployed as M2, the similar advantages can be obtained. Even when atleast one type of nonmetallic elements selected from N, O, C is employedas X, the similar advantages can be obtained.

In the fourth example, the film structure similar to the first to fifthvariations of the first example can be applied.

FIFTH EXAMPLE

In the magnetoresistive elements shown in the first to fourth examples,the spacer layer 14 is made of Cu. Here, it was examined whether or notthe advantages of the present invention can be achieved in themagnetoresistive element having a resistance adjusting layer as thespacer layer 14. A resistance adjusting layer 142 used herein is NOL(Nano Oxide Layer) made of Al—O having metal paths formed of Cu. A Cumetal path passes through Al—O as an insulating layer, andohmic-connects the magnetization free layer and the magnetizationpinning layer.

A magnetoresistive element of the fifth example is shown in FIG. 7. Themagnetoresistive element of the fifth example includes the lowerelectrode 21, the under layer 11, the pinning layer 12, the pin layer13, the spacer layer 14, the free layer 15, the cap layer 16, and theupper electrode 22, which are formed sequentially from the bottom on thesubstrate. In the fifth example, the synthetic spin valve structure isemployed, and the magnetic compound layer expressed by the formulaM1_(a)M2_(b)X_(c) is employed as the upper pin layer 133 of the pinlayer 13 located on the spacer side and the free layer 15.

The spacer layer 14 includes a metal layer 141, the resistance adjustinglayer 142, and a metal layer 143. The resistance adjusting layer 142 isNOL (Nano Oxide Layer) formed of an insulating layer 142 b made of Al—Oand having metal paths 142 a made of Cu therein. The insulating layer142 b of the resistance adjusting layer 142 may be formed of Si, Mg, Ta,Ti, Zr, Zn, or the like or an oxide of an alloy containing theseelements as a main component, except Al—O. Also, the insulating layerconverted from the oxidized metal layer is not limited to the oxide, andnitride or oxanitride may be employed. As the material of the metal path142 a of the resistance adjusting layer 142, the material that is hardto be oxidized and has a low specific resistance is desirable, and Cu,Au, Ag, or the like can be employed.

The metal layer 141 acts as a supply source of the metal path 142 a informing the resistance adjusting layer 142, and has a function as abarrier layer for preventing such a situation that the underlying pinlayer 13 comes into contact with the oxide of the resistance adjustinglayer 142 and is excessively oxidized. Therefore, the material that ishard to be oxidized and has a low specific resistance is desirable, andCu, Au, Ag, or the like can be employed.

The metal layer 143 has a function as a barrier layer for preventingsuch a situation that the overlying free layer 15 comes into contactwith the oxide of the resistance adjusting layer 142 and is excessivelyoxidized, and Cu, Au, Ag, or the like can be employed.

In the fifth example, constituent elements except the spacer layer 14are similar to those in the first example, and the magnetoresistiveelements are manufactured by using the magnetic compound Co—Ti—O [3 nm]as the upper pin layer 133 and the free layer 15 while changing acomposition ratio of Co—Ti—O. Also, as a comparative example, themagnetoresistive element in which the conventional material Co₉₀Fe₁₀ wasused as the upper pin layer 133 and the free layer 15 is alsomanufactured.

When the magnetoresistive elements according to the fifth example areevaluated, it is confirmed that the MR ratio higher than that in thecomparative example is obtained by the magnetoresistive element that ismanufactured at the Co—Ti—O composition ratio in particular range. Thereason for such improvement in the MR ratio can be considered such thatthe magnetic compound has the high spin polarizability by attaining aproper composition ratio.

In the fifth example, the magnetoresistive elements having thecomposition ratio given in the composition formula expressed byCo_(a)Ti_(b)O_(c) shown in following Table 5 are manufactured. (Here,“a”, “b”, “c” are an atomic percent [at %].) In Table 5, remarksindicating whether the MR ratio is improved in each composition ratherthan comparative example or not is shown together.

TABLE 5 Improvement in MR ratio sample No. Magnetic Material toComparative Example (Comp. Example) Co₉₀Fe₁₀ — A00 E01 Co₆₉Ti₁₀O₂₁ notimproved E02 Co₆₈Ti₁₀O₂₂ improved E03 Co₆₀Ti₁₀O₃₀ particularly improvedE04 Co₄₀Ti₁₀O₅₀ particularly improved E05 Co₁₅Ti₁₀O₇₅ particularlyimproved E06 Co₅Ti₁₀O₈₅ improved E07 Co₄Ti₁₀O₈₆ not improved E08Co₆₉Ti₉O₂₂ not improved E09 Co₅Ti₇₃O₂₂ improved E10 Co₄Ti₇₄O₂₂ notimproved E11 Co₄Ti₆₆O₃₀ not improved E12 Co₄Ti₃₀O₆₆ not improved E13Co₅Ti₆₅O₃₀ particularly improved E14 Co₁₀Ti₅₀O₄₀ particularly improvedE15 Co₃₀Ti₃₀O₄₀ particularly improved E16 Co₂₀Ti₂₀O₆₀ particularlyimproved

The MR ratio of the comparative example A00 is 5%. It is confirmed thatthe magnetoresistive element manufactured in ranges of 5≦a≦68, 10≦b≦73,and 22≦c≦85 has the MR ratio of 6% or more, which exceeds thecomparative example. Also, the particularly high MR ratio in excess of20% is confirmed in the magnetoresistive element manufactured in therange of 30≦c≦75 among the above ranges. Thus, improvement in the MRratio due to use of the magnetic compound is particularly remarkablynoticed.

With the above, in the magnetoresistive element having the spacer layer14 with the Al—O NOL structure having the Cu metal paths, the advantagefor improving the MR ratio by employing the magnetic compound M1-M2-X ofthe present invention can be still maintained.

When an added amount of a composition ratio “b” of the non-magnetic 3dtransition metal element Ti, V, Cr, Mn is too small in the magneticcompound expressed by the formula M1_(a)M2_(b)X_(c), a contribution ofthe non-magnetic 3d transition metal element to the spin-dependentconduction is reduced. Therefore, it is preferable that the compositionratio “b” should be set to 10≦b. However, when an added amount is toolarge, the magnetic 3d transition metal element is reduced relatively,and the bonding between the non-magnetic 3d transition metal element andthe magnetic 3d transition metal element is reduced. Thus, a magnetismof the non-magnetic 3d transition metal element is weakened. Therefore,it is more preferable that the composition ratio “b” should be set to10≦b≦73.

In order to obtain an effect of encouraging a change of the bandstructures of the non-magnetic 3d transition metal element and themagnetic 3d transition metal element, preferably a composition ratio “c”of the nonmetallic element N, O, C in the magnetic compound expressed bythe formula M1_(a)M2_(b)X_(c) should be set to 22≦c. However, when anadded amount is too large, the non-magnetic 3d transition metal elementand the magnetic 3d transition metal element are reduced relatively, andthen an amount of elements to bear the spin-dependent conduction isreduced. Therefore, it is desirable that the composition ratio “c”should be set to 22≦c≦85. In addition, in order to obtain the large spinpolarizability in a situation that this element is bonded to most of theelements contained in the non-magnetic 3d transition metal element andthe magnetic 3d transition metal element, the particularly high MR ratiocan be obtained when the composition ratio “c” should be set to 30≦c≦75.

When an added amount of a composition ratio “a” of the magnetic 3dtransition metal element Co, Fe, Ni is too small in the magneticcompound expressed by the formula M1_(a)M2_(b)X_(c), the bonding betweenthe non-magnetic 3d transition metal element and the magnetic 3dtransition metal element is reduced. Thus, a magnetism of thenon-magnetic 3d transition metal element is weakened. However, when anadded amount is too large, the composition ratio “b” of the non-magnetic3d transition metal element and the composition ratio “c” of thenonmetallic element are reduced relatively, and then an effect ofincreasing the spin polarizability due to the addition of thenon-magnetic 3d transition metal element and the nonmetallic element, asalready described, is weakened. Therefore, it is more desirable that thecomposition ratio “a” should be set to 5≦a≦68.

In the fifth example, as for the compositions in the magnetic compoundformula M1_(a)M2_(b)X_(c), Co is employed as M1, Cr is employed as M2,and O is employed as X. Even when at least one type of magnetic 3dtransition metal elements selected from Co, Fe, Ni is employed as M1,the similar advantages can be obtained. Even when at least one type ofnon-magnetic 3d transition metal elements selected from Ti, V, Cr, Mn isemployed as M2, the similar advantages can be obtained. Even when atleast one type of nonmetallic elements selected from N, O, C is employedas X, the similar advantages can be obtained.

Sixth Variation: Spacer Layer is CCP-NOL and Free Layer has StackedStructure

As a variation (sixth variation) of the fifth example shown in FIG. 7, amagnetoresistive element in which the resistance adjusting layer 142 isused as the spacer layer and a stacked structure composed of themagnetic compound layer and the ferromagnetic thin film layer is used asthe free layer is shown in FIG. 8.

In FIG. 8, the magnetoresistive element of the sixth variation includesthe lower electrode 21, the under layer 11, the pinning layer 12, thepin layer 13, the spacer layer 14, the free layer 15, the cap layer 16,and the upper electrode 22, which are formed sequentially from thebottom on the substrate. In the sixth variation, the free layer 15 isformed as the stacked structure composed of the lower free layer 151 andthe upper free layer 152. Also, in the sixth variation, the syntheticspin valve structure is employed, and the magnetic compound layerM1-M2-X is employed as the upper pin layer 133 of the pin layer 13located on the spacer side and the lower free layer 151.

When a soft magnetic film that is superior in the soft magneticcharacteristic to the magnetic compound layer is employed as theferromagnetic thin film layer used as the upper free layer 152, amagnetic field responsibility can be improved. A NiFe alloy can beemployed as the material of the ferromagnetic thin film layer used asthe upper free layer 152. Ni_(x)Fe_(100-x) (x=about 78 to 85) ispreferable as the composition of the NiFe alloy, and about 2 to 5 nm ispreferable as a film thickness of the NiFe layer. When the NiFe layer isnot employed, the free layer obtained by stacking a CoFe layer or a Felayer of 1 nm to 2 nm thickness and a very thin Cu layer of about 0.1 nmto 0.8 nm thickness in plural alternately may be employed. Also,Co₉₀Fe₁₀ whose soft magnetic characteristic is particularly stable outof the CoFe alloy may be employed. When the CoFe alloy similar toCo₉₀Fe₁₀is employed, preferably a film thickness should be set to 0.5 nmto 4 nm. When the CoFe alloy having other composition is employed,preferably a film thickness should be set to 0.5 nm to 2 nm to maintainthe soft magnetic characteristic.

In the sixth variation, since the resistance adjusting layer 142 is usedas the spacer layer 14 and a current is constricted near the metal paths142 a, a spin-dependent scattering effect is increased in the lower freelayer 151 of the free layer 15 rather than the upper free layer 152.Therefore, in case the resistance adjusting layer 142 is used as thespacer layer 14 and the stacked type layer is used as the free layer, itis desirable that the magnetic compound M1-M2-X as the material whosespin-dependent scattering effect is large should be arranged as thelower free layer 151.

However, in the following case, the ferromagnetic thin film layer may beemployed as the lower free layer 151 and the magnetic compound layerM1-M2-X may be employed as the upper free layer 152. In case thespin-dependent scattering of the magnetic compound is consideredseparately as the bulk scattering and the interface scattering, in somecases such a situation is caused depending on the method ofmanufacturing the magnetic compound layer M1-M2-X that thespin-dependent bulk scattering becomes higher than the conventionalferromagnetic material used as the ferromagnetic thin film layer and thespin-dependent interface scattering becomes lower than the conventionalferromagnetic material used as the ferromagnetic thin film layer. Insuch case, the ferromagnetic thin film layer may be employed as thelower free layer 151 and the magnetic compound layer M1-M2-X may beemployed as the upper free layer 152. Only the spin-dependent bulkscattering effect of the magnetic compound layer is utilized effectivelyby arranging the ferromagnetic thin film layer on the spacer layerinterface, so that the high MR ratio can be obtained. Also, in the sixthexample, the two-layered stacked structure composed of the magneticcompound layer and the ferromagnetic thin film layer is employed, butthe three-layered stacked structure composed of the ferromagnetic thinfilm layer/magnetic compound layer/ferromagnetic thin film layer, or thelike may be employed.

Similar to the first example, Co—Ti—O can be employed as the magneticcompound M1-M2-X. In the sixth variation, the similar advantages tothose in the first example can be obtained. As for the compositions inthe magnetic compound M1-M2-X, even when at least one type of magnetic3d transition metal elements selected from Co, Fe, Ni is employed as M1,the similar advantages can be obtained. Even when at least one type ofnon-magnetic 3d transition metal elements selected from Ti, V, Cr, Mn isemployed as M2, the similar advantages can be obtained. Even when atleast one type of nonmetallic elements selected from N, O, C is employedas X, the similar advantages can be obtained.

In the sixth variation, a single layer of the magnetic compound M1-M2-Xis employed as the pin layer, but the conventional material may beemployed. Also, in combination with a seventh variation describedhereunder, both magnetic layers of the free layer and the pin layer maybe formed as the stacked structure composed of the magnetic compoundlayer and the ferromagnetic thin film layer.

Seventh Variation: the Spacer Layer is CCP-NOL and Pin Layer has StackedStructure

As a variation (seventh variation) of the fifth example shown in FIG. 7,a magnetoresistive element in which the resistance adjusting layer 142is used as the spacer layer 14 and a stacked structure composed of themagnetic compound layer and the ferromagnetic thin film layer is used asthe pin layer is shown in FIG. 9.

In FIG. 9, the magnetoresistive element of the seventh variationincludes the lower electrode 21, the under layer 11, the pinning layer12, the pin layer 13, the spacer layer 14, the free layer 15, the caplayer 16, and the upper electrode 22, which are formed sequentially fromthe bottom on the substrate. In the seventh variation, the syntheticspin valve structure is employed, and a stacked film composed of theupper pin layer lower layer 1331 and the upper pin layer upper layer1332 is used as the upper pin layer 133 of the pin layer 13 located onthe spacer side and the magnetic compound layer expressed by the formulaM1_(a)M2_(b)X_(c) is employed as the upper pin layer upper layer 1332and the free layer 15.

When the material that can be pinned more easily in one direction thanthe magnetic compound is employed as the ferromagnetic thin film layerused as the upper pin layer lower layer 1331, the pin characteristic canbe improved. As the ferromagnetic thin film layer material used as theupper pin layer lower layer 1331, a single metal such as Co, Fe, Ni, orthe like or all alloy materials containing any one element of theseelements can be employed.

In the seventh variation, since the resistance adjusting layer 142 isused as the spacer layer 14 and a current is constricted near the metalpaths 142 a, a spin-dependent scattering effect is increased in theupper pin layer upper layer 1332 of the upper pin layer rather than theupper pin layer lower layer 1331. Therefore, in case the resistanceadjusting layer 142 is used as the spacer layer 14 and the stacked typelayer is used as the pin layer, it is desirable that the magneticcompound M1-M2-X as the material whose spin-dependent scattering effectis large should be arranged as the upper pin layer upper layer 1332.

That is, from a viewpoint of the pin characteristic and a viewpoint ofthe MR ratio, it is desirable that the magnetic compound M1-M2-X shouldbe arranged as the upper pin layer upper layer 1332.

However, in the following case, the three-layered stacked structurecomposed of the ferromagnetic thin film layer/magnetic compoundlayer/ferromagnetic thin film layer, or the more may be employed. Incase the spin-dependent scattering of the magnetic compound isconsidered separately as the bulk scattering and the interfacescattering, in some cases such a situation is caused depending on themethod of manufacturing the magnetic compound layer M1-M2-X that thespin-dependent bulk scattering becomes higher than the conventionalferromagnetic material used as the ferromagnetic thin film layer and thespin-dependent interface scattering becomes lower than the conventionalferromagnetic material used as the ferromagnetic thin film layer. Insuch case, only the spin-dependent bulk scattering effect of themagnetic compound layer is utilized effectively by arranging theferromagnetic thin film layer on the spacer layer interface, so that thehigh MR ratio can be obtained.

Similar to the first example, Co—Ti—O can be employed as the magneticcompound M1-M2-X. In the seventh variation, the similar advantages tothose in the first example can be obtained. As for the compositions inthe magnetic compound M1-M2-X, even when at least one type of magnetic3d transition metal elements selected from Co, Fe, Ni is employed as M1,the similar advantages can be obtained. Even when at least one type ofnon-magnetic 3d transition metal elements selected from Ti, V, Cr, Mn isemployed as M2, the similar advantages can be obtained. Even when atleast one type of nonmetallic elements selected from N, O, C is employedas X, the similar advantages can be obtained.

In the seventh variation, a single layer of the magnetic compoundM1-M2-X is employed as the free layer, but the conventional material maybe employed. Also, in combination with sixth variation, both magneticlayers of the free layer and the pin layer may be formed as the stackedtype.

Hereinafter, applications of the magnetoresistive element according tothe embodiment of the present invention will be explained hereunder.

In the embodiment of the present invention, an element resistance RA ofthe magnetoresistive element should be set preferably to 500 mΩ/μm² orless from a viewpoint of the high density compatibility, and morepreferably to 300 mΩ/μm². The element resistance RA is calculated bymultiplying an element resistance R of the CPP element by an effectivearea A of a current feeding portion of the spin valve film. Here, theelement resistance R can be measured directly. In contrast, since theeffective area A of the current feeding portion of the spin valve filmis a value that depends upon an element structure, care must be taken indeciding the effective area A.

For example, when the overall spin valve film is patterned as aneffective sensing area, an area of the overall spin valve filmcorresponds to the effective area A. In this case, from a viewpoint thatthe element resistance should be set adequately, the area of the spinvalve film should be set to at least 0.04 μm² or less, and should be setto 0.02 μm² or less when a recording density is set to 200 Gbpsi ormore.

However, when a lower electrode or an upper electrode whose area issmaller than the spin valve film is formed to contact the spin valvefilm, the area of the lower electrode or the upper electrode correspondsto the effective area A of the spin valve film. When the areas of thelower electrode and the upper electrode are different respectively, thesmaller area of the electrode corresponds to the effective area A of thespin valve film. In this case, from a viewpoint that the elementresistance should be set adequately, the smaller area of the electrodeshould be set to at least 0.04 μm² or less.

In the case of examples shown in FIG. 10 and FIG. 11, which will bedescribed later, because the smallest area of the spin valve film 10 inFIG. 10 corresponds to the portion that contacts the upper electrode251, this width is considered as a track width Tw. Also, because theportion that contacts the upper electrode 251 is also smallest in heightin FIG. 11, this width is considered as a height length D. The effectivearea A of the spin valve film is considered like A=Tw×D.

In the magnetoresistive element according to the embodiment of thepresent invention, the resistance R between the electrodes can bereduced to 100 Ω or less. This resistance R is a resistance value thatis measured between two electrode pads of a playback head portion fittedto a top end of a head gimbal assembly (HGA), for example.

Magnetic Head

FIG. 10 and FIG. 11 show a state that the magnetoresistive elementaccording to the embodiment of the present invention is incorporatedinto the magnetic head. FIG. 10 is a sectional view when themagnetoresistive element is cut along the almost parallel direction tothe medium facing surface that opposes to the magnetic recording medium(not shown). FIG. 11 is a sectional view when the magnetoresistiveelement is cut along the perpendicular direction to the medium facingsurface ABS.

The magnetic head shown in FIG. 10 and FIG. 11 has the so-called hardabutted structure. A magnetoresistive film 10 is the magnetoresistivefilm described above. The lower electrode 250 and the upper electrode251 are provided on and under the magnetoresistive film 10 respectively.In FIG. 10, a bias magnetic field applying film 41 and an insulatingfilm 42 are stacked and provided on both side surfaces of themagnetoresistive film 10. As shown in FIG. 11, a protection layer 43 isprovided on the medium facing surface of the magnetoresistive film 10.

A sense current applied to the magnetoresistive film 10 is fed in thedirection almost perpendicular to the film surface by the lowerelectrode 250 and the upper electrode 251 arranged under and on themagnetoresistive film 10, as indicated with an arrow A. Also, a biasmagnetic field is applied to the magneto-resistive film 10 by a pair ofbias magnetic field applying films 41, 41 provided on the right and leftsides. The magnetic anisotropy of the free layer of the magnetoresistivefilm 10 is controlled by the bias magnetic field to obtain the singledomain, so that the magnetic domain structure can be stabilized and aBarkhausen noise generated due to movement of magnetic walls can besuppressed.

Since an S/N ratio of the magnetoresistive film 10 is improved, a highsensitivity magnetic playback can be realized when this magnetoresistivefilm is applied to the magnetic head.

Hard Disk and Head Gimbal Assembly

The magnetic head shown in FIG. 10 and FIG. 11 can be incorporated intothe magnetic recording/reproducing apparatus when it is installed intothe recording/playing integrated magnetic head assembly.

FIG. 12 is a pertinent perspective view showing a schematicconfiguration of such magnetic recording/reproducing apparatus. That is,a magnetic recording/reproducing apparatus 150 of the present embodimentis the device of the type using a rotary actuator. In FIG. 12, amagnetic disk 200, which serves as a magnetic recording medium, isfitted to a spindle 152 and is turned in the arrow A direction by amotor (not shown) that responds to a control signal fed from a drivingunit controlling portion (not shown). The magnetic recording/reproducingapparatus 150 of the present embodiment may be equipped with a pluralityof magnetic disks 200.

A head slider 153 for recording/reproducing the information stored inthe magnetic disk 200 is fitted to a top end of a thin film-likesuspension 154. The magnetic head containing the magnetoresistiveelement according to any one of embodiments is mounted near the top endof the head slider 153.

When the magnetic disk 200 is turned, the medium facing surface (ABS) ofthe head slider 153 is held at a predetermined floating height from asurface of the magnetic disk 200. Otherwise, a so-called contact-typeslider that contacts the magnetic disk 200 may be employed.

The suspension 154 is connected to one end of an actuator arm 155. Avoice coil motor 156 as one type of linear motor is provided to theother end of the actuator arm 155. The voice coil motor 156 includes adriving coil (not shown) wound in a bobbin portion, and a magneticcircuit that consists of a permanent magnet and an opposing yoke opposedto put the coil therebetween.

The actuator arm 155 is held by ball bearings (not shown) provided toupper and lower portions of a spindle 157, and can be turned/slid by thevoice coil motor 156.

FIG. 13 is an enlarged perspective view when the head gimbal assemblyposition ahead of the actuator arm 155 is viewed from the disk side.That is, an assembly 160 has the actuator arm 155, and the suspension154 is connected to one end of the actuator arm 155. The head slider 153having the magnetic head containing the magnetoresistive elementaccording to any one of the above embodiments is fitted to a top end ofthe suspension 154. The suspension 154 has lead wires 164 used to writeand read the signal, and the lead wires 164 and respective electrodes ofthe magnetic head incorporated into the head slider 153 are connectedelectrically to each other. In FIG. 13, 165 denotes an electrode pad.

According to thus described configuration, since the magnetic headincluding the foregoing magnetoresistive element is equipped, theinformation recorded magnetically on the magnetic disk 200 can be readat high recording density without fail.

Magnetic Memory

Next, the magnetic memory into which the magnetoresistive elementaccording to the embodiment of the present invention is incorporatedwill be explained hereunder.

The magnetic memory such as the magnetic random access memory (MRAM) inwhich memory cells are arranged in a matrix fashion, for example, andthe like can be implemented by using the magnetoresistive elementaccording to the embodiment of the present invention.

FIG. 14 is a view showing an example of a matrix arrangement of themagnetic memory according to the embodiment of the present invention.This FIG. 14 shows a circuit configuration when the memory cells arearranged in an array fashion. A column decoder 350 and a row decoder 351are provided to select one bit in the array. The bit informationrecorded in a magnetic recording layer (free layer) in themagnetoresistive film 10 can be read by selecting uniquely a switchingtransistor 330, which is to be turned ON, via a bit line 334 and a wordline 332 and then sensing the transistor by a sense current 352. Whenthe bit information is written, the magnetic field generated bysupplying a writing current to a particular writing word line 323 and abit line 322 is applied to a particular bit.

FIG. 15 is a view showing another example of a matrix arrangement of themagnetic memory according to the embodiment of the present invention. Inthis case, the bit line 322 and the word line 334 wired in a matrixfashion are selected by decoders 361, 362 respectively, and a particularmemory cell in the array is selected. Each memory cell has aseries-connected structure of the magnetoresistive element 10 and adiode D. Here, the diode D has a function to prevent the event that thesense current detours into the memory cells except the selectedmagnetoresistive element 10. The writing is executed by the magneticfield generated by supplying the writing current to the particular bitline 322 and the writing word line 323.

FIG. 16 is a sectional view showing a substantial part of the magneticmemory according to the embodiment of the present invention. FIG. 17 isa sectional view taken along a XVII-XVII line shown in FIG. 16. Thestructure shown in these Figures corresponds to one-bit of the memorycell contained in the magnetic memory shown in FIG. 14 and FIG. 15. Thismemory cell has a memory element portion 311 and an address selectingtransistor portion 312.

The memory element portion 311 has the magnetoresistive element 10 and apair of wirings 322, 324 connected to this magnetoresistive element. Themagnetoresistive element 10 is the magnetoresistive element according tothe above embodiment.

In contrast, the switching transistor 330 connected through vias 326 andembedded wirings 328 is provided in the address selecting transistorportion 312. This switching transistor 330 executes a switchingoperation in response to a voltage applied to the gate 332, and controlsthe open/close of the current path between the magnetoresistive element10 and the word line 334.

Also, the writing wiring 323 is provided below the magnetoresistiveelement 10 in the direction almost perpendicular to the wiring 322.These writing wirings 322, 323 can be formed of aluminum (Al), copper(Cu), tungsten (W), tantalum (Ta), or an alloy containing any one ofthese elements, for example.

In the memory cell having such configuration, when the bit informationis written into the magnetoresistive element 10, a writing pulse currentis supplied to the wirings 322, 323 and then the magnetization of therecording layer of the magnetoresistive element is invertedappropriately by applying a synthesized magnetic field induced by thesecurrents.

Also, when the bit information is read, the sense current is fed throughthe wiring 322, the magnetoresistive element 10 containing the magneticrecording layer, and a lower electrode 324, and a resistance value ofthe magnetoresistive element 10 or a change of the resistance value ismeasured.

Since the magnetoresistive element according the above embodiment isutilized, the magnetic memory according to the embodiment of the presentinvention can keep the sure writing and execute the reading surely bycontrolling the magnetic domain of the recording layer surely even whena cell size is miniaturized.

Other Embodiment

The embodiment of the present invention is not limited to the abovedescribed embodiment, and can be extended and varied. The extended andvaried embodiments are also within the technical scope of the presentinvention.

Those skilled in the art can select appropriate structure of themagnetoresistive film, and shapes and materials of electrode, biasapplying film, insulating film, and the like from the publicly-knownranges. Thus, the present invention can be embodied similarly and thesimilar advantages can be attained.

For example, when the magnetic shielding is attached on and under theelement in applying the magnetoresistive element to the playbackmagnetic head, a sensing resolution of the magnetic head can bespecified. Also, the embodiment of the present invention can be appliedto the magnetic head or the magnetic reproducing device of not only thelongitudinal magnetic recording system but also the vertical magneticrecording system. In addition, the magnetic reproducing device of thepresent invention may of the fixed type in which the particularrecording medium is stably fitted, or the so-called “removable” type inwhich the recording medium can be exchanged.

In addition, all magnetoresistive elements, magnetic heads, magneticstoring/reproducing devices and magnetic memories, which the thoseskilled in the art can embody appropriately by applying a change indesign based on the magnetic head and the magnetic recording/reproducingapparatus as the embodiment of the present invention, also belong to ascope of the present invention.

It is to be understood that the present invention is not limited to theabove-described specific embodiment thereof and various changes,modifications, etc., may be made without departing from the spirit andthe scope of the invention.

1. A magnetoresistive element comprising: a first magnetic layer whosemagnetization direction is substantially pinned toward one direction; asecond magnetic layer whose magnetization direction is changed inresponse to an external magnetic field; and a spacer layer providedbetween the first magnetic layer and the second magnetic layer, whereinat least one of the first magnetic layer and the second magnetic layercomprises a magnetic compound layer including a magnetic compound thatis expressed by M1_(a)M2_(b)O_(c) (where 5≦a≦68, 10≦b≦73, and 22≦c≦85),wherein M1 is at least one element selected from the group consisting ofCo, Fe, and Ni, wherein M2 is at least one element selected from thegroup consisting of Ti, V, and Cr.
 2. The magnetoresistive elementaccording to claim 1, wherein c satisfies 30≦c≦75.
 3. Themagnetoresistive element according to claim 1, wherein the spacer layeris a conductor.
 4. The magnetoresistive element according to claim 1,wherein the magnetic compound has an amorphous crystal structure.
 5. Themagnetoresistive element according to claim 1, wherein the magneticcompound layer has a film thickness in a range from 0.5 nm to 5 nm.
 6. Amagnetoresistive head comprising the magnetoresistive element accordingto claim
 1. 7. A magnetic recording/reproducing apparatus comprising:the magnetoresistive head according to claim 6; and a magnetic recordingmedium.
 8. A magnetic memory comprising the magnetoresistive elementaccording to claim 1.